Yeah then it's definitely from the build-up in your tap water, maybe chlorine damage even. If possible try to use clean water like RO water or distilled but other than the small spots your plants look quite decent. PH is really important, you could get small PH test strips that you can just dip in the water to check it or even better the little plastic vial you put indicator drops in and judge the PH by the color. You can find this anywhere that sells pool test supplies but don't use their PH up and down it's the wrong stuff lol.

Lemon juice will lower PH and baking soda will raise it but baking soda is high in sodium and must be used very sparsely or you will have toxic sodium levels.
Better to get the real Ph up and down made for plants from a hydro shop.

Definitely get your PH under control and with clean water you should have literally perfect plants considering your plants already look good and well taken care of.